The contractor was to receive from Upjohn Laboratories approximately 100,000 tablets of Erythromycin (E-mycin 333mg) and 120,000 identical appearing placebo tablets in bulk shipments. These were to be repackaged, on separate days to prevent mixture of the pills, into blister packs containing 21 pills each of either active drug or placebo designed for use in the Vaginal Infection and Prematurity Study. After packaging they were to be bundled in sets of 10, packed into boxes labelled active or placebo and shipped to the Data Coordinating Center in North Carolina. The Data Coordinating Center them labelled the drug with appropriate codes to preserve the blinded nature of the study and delivered them to the clinical centers involved in the study for use in a double-blind placebo controlled clinical trial.